[2nd Ed.] [I have retained the remarks which I ventured at first to make on the System of M. Agassiz; but I believe the opinion of the most philosophical ichthyologists to be that Cuvier’s System was too exclusively based on the internal skeleton, as Agassiz’s was on the external skeleton. In some degree both systems have been superseded, while all that was true in each has been retained. Mr. Owen, in his Lectures on Vertebrata (1846), takes Cuvierian characters from the endo-skeleton, Agassizian ones from the exo-skeleton, Linnæan ones from the ventral fins, Müllerian ones from the air-bladder, and combines them by the light of his own researches, with the view of forming a system more truly natural than any preceding one.
As I have said above, naturalists, in their progress towards a Natural [431] System, are guided by physiological relations, latently in Botany, but conspicuously in Zoology. From the epoch of Cuvier’s Règne Animal, the progress of Systematic Zoology is inseparably dependent on the progress of Comparative Anatomy. Hence I have placed Cuvier’s Classification of animal forms in the next Book, which treats of Physiology.]
BOOK XVII.
ORGANICAL SCIENCES.
HISTORY OF PHYSIOLOGY
AND
COMPARATIVE ANATOMY.
Fearful and wondrous is the skill which moulds
Our body’s vital plan,
And from the first dim hidden germ unfolds
The perfect limbs of man.
Who, who can pierce the secret? tell us how
Something is drawn from naught,
Life from the inert mass? Who, Lord! but thou,
Whose hand the whole has wrought?
Of this corporeal substance, still to be,
Thine eye a survey took;
And all my members, yet unformed by thee,
Were written in thy book.
Psalm cxxxix. 13–16.